Geomorphology Flashcards
(65 cards)
1
Q
Agents of weathering
A
- Water
- Ice
- Acids
- Salts
- Plants
- Animals
- Changes in temperature
2
Q
Types of physical weathering
A
- Temperature change
- Freeze thaw/ Frost Shattering
- Abrasion - Wind, Rain, Waves
3
Q
Degree of chemical weathering depends on
A
- Type of rock
- Temperature
4
Q
How acidic rain is made:
A
- Fossil fuels are burnt up, releasing oxides such as nitrogen, carbon and sulphur into the atmosphere
- These oxides combine with the moisture in the air, and form nitric acid, sulphuric acid, carbonic acid
5
Q
Types of Biological weathering
A
- Trees and other plants
- Tiny organisms
- Burrowing animals
6
Q
Difference between weathering, erosion, deposition
A
Weathering: occurs on the spot
Erosion: weathered rocks or minerals are transported away
Deposition: comes to rest
7
Q
Transporting agents
A
- Gravity
- Water
- Wind
- Ice
8
Q
River valley sections
A
- Upper Course (young)
- Middle Course (aged/mature)
- Lower Course (old)
9
Q
Rivers goal
A
To erode all land to sea level
10
Q
Agents of erosion
A
- Rivers
- Oceans
- Winds
- Glaciers
11
Q
Meander is also called
A
River bend
12
Q
Importance of rivers to man
A
- For our survival: water
- For food
- Irrigation, watering our crops
- Transportation
- Energy, hydro electric power
- Leisure
13
Q
Characteristics of upper course
A
- Closer to the source
- Steep gradient
- Small river and flows quickly
14
Q
Features in upper course
A
- V- shaped valleys
- Interlocking spurs
- Rapids
- Waterfalls
- Gorges and canyons
15
Q
Types of erosion
A
- Hydraulic action
- Abrasion
- Attrition
- Solution
16
Q
Types of transportation
A
- Traction
- Saltation
- Suspension
- Solution
17
Q
V - shaped valleys
A
Deep valleys with steep sides
18
Q
Interlocking spurs
A
- Erosion outside the banks and vertical erosion
- Results in ridges of high land (spurs) to project towards the river, decreasing in height towards the river
19
Q
Waterfalls are commonly formed
A
When a river crosses a band of hard or resistant rock
20
Q
White water shows
A
A lot of turbulence
21
Q
What results in rapids
A
Friction that is caused
22
Q
River’s velocity depends on
A
- Gradient
- Smoother the channel/path
- Volume
23
Q
Rapids
A
Steep slope, with rough river bed (uneven due to alternating bands of soft and hard rock)
24
Q
Characteristics of Middle Course
A
- Gradient not as steep as Upper Course
- Lateral erosion (erosion of the banks) more effective than vertical
- More wider, open appearance
- Some deposition takes place
- Meanders are common
25
Features in Middle Course
- Meanders: river cliffs and slip-off slopes
- Ox-bow lakes
26
Meanders with river cliffs and slip-off slopes
- Outside banks are undercut creating river cliffs
- Inside banks where water flows more slowly with deposition. Giving rise to gentler slopes/slip-off slopes
27
Ox-bow lakes
- Sometimes meanders become so pronounced that only a narrow neck of land is left
- When a river is in flood the neck breaks
- Deposition then takes place sealing off the ends of the meander
28
Characteristics in the lower course
- Nearest the sea
- Gradient is gentler
- River flows slowly
- Volume of water is greater
- Transportation is mainly suspension and solution
- Deposition is more important than erosion
29
Features in a lower course
- Floodplain
- Levees
- Braiding
- Deltas
30
Floodplains
- Middle and lower course
- Alluvium is deposited on valley floor
31
Levees
- River floods, depositing material on flood plains
- Heavier/larger material are deposited near the river, lighter/smaller sediment is carried/deposited further away
- After successful floods, natural embankments called levees are created
32
Braiding
- Occurs when the river divides over various distances into two or more channels
- Occurs when the river carries a large load/the volume of the river changes rapidly from season to season
33
Deltas form under these conditions
- River carries large amount of sediment
- Sea is relatively calm (no waves or strong currents to carry sediment away)
- Sea is not too deep
- River flows slowly
- Vertical difference between high tide and low tide (tidal range) is not too great
34
Traction
In the upper course. Big rocks roll/slide down with the water
35
Saltation
In the upper course. Pebbles (smaller) are bounced with the movement of the water
36
Suspension
In the middle and lower course. Tiny grains of sand and silt/clay are held in the body of the water carried along with the flow.
37
Solution
In middle and lower course. Minerals that are dissolved in water are carried along in solution
38
Size of wave is determined by
- Speed of wind
- Length of time the wind has been blowing
- Distance of sea it has travelled over (fetch)
39
Hydraulic action: blow holes
Power of the waves forces air into cracks, compresses and blows the rock apart as the pressure is released
40
Constructive waves
- Build up beaches
- Large swash
- Lower than destructive waves
- Longer wavelength
- Made when the sea is calm
41
Destructive waves
- Much larger and powerful
- Made during a storm
- Travelled a long way
- Stronger backwash
- Short distance between peaks
- Much taller
42
Features of Coastal Erosion
- Cliffs
- Notches
- Wavecut platforms
- Headlands
- Bays
- Caves
- Arches
- Stacks
43
Cliffs form where…
There is harder, more resistant rock (limestone/chalk)
44
Wave erosion is strongest where…
The large waves break against the base of the cliff
45
Headlands and bays are created by
- Differential erosion and formed in alternating bands of different rock types
- Meets the coast at right angles, softer rocks erode faster to form sheltered bays
- Harder rocks are more resistant to form exposed headlands
46
Long shore drift: transportation of particles along a coastline is influenced by:
- Strength of waves
- Angle at which waves strike the shoreline
47
Spits form where:
- The coastline changes direction
- Longshore drift continues to move material along the beach
48
Coastal methods of Transport
Longshore drift
49
Coast: Features of deposition
Spits
50
Longshore drift will…
Deposit material in the sea after the coastline has changed direction
51
Spit cannot…
Develop right across the bay as a river’s estuary prevents build-up of sand
52
Sand spits often have a…
Curved/hooked end
53
Sand spits end is created by:
- Secondary wind
- Wave direction
These causes waves to strike from a different direction
54
Spits create…
An area of calmer water, sheltered by the spit from the waves. A lagoon can develop in this sheltered area.
55
Lagoon is also called
Salt marsh or dry land
56
Coastal landforms
- Bays
- Beaches
- Capes
- Caves
- Headlands
- Islands
- Lagoons
- Peninsulas
- Reefs
- Rocky shores
- Sea cliffs
- Tidal pools
57
Peninsula
- Connected by a thin land mass
- Almost an island
- Bordered by water on 3 sides
58
Cape
Bordered by water on 2 sides
59
Management of the coast
- Hard Engineering
- Soft Engineering
60
Hard Engineering Examples
- Sea walls = 75 years life span
- Revetments = sloped structures
- Groynes/Piers
- Rock armour/rickrap
61
Hard Engineering Advantages
- Immediately stops erosion
- Encourages deposition
62
Hard Engineering Disadvantages
- High impact on environment
- Expensive
- Less sustainable
- Short term
63
Soft Engineering Examples
- Beach nourishment
- Sand dune stabilisation
- Managed realignment
64
Soft Engineering Advantages
- Long term
- Cheaper
- Low impact on environment
- More sustainable
65
Soft Engineering Disadvantages
Less effective against erosion and flooding
